Part:BBa_K4170091

lac Repressor

The lac repressor binds to the lac operator to inhibit transcription in E. coli. This inhibition can be relieved by adding lactose or isopropyl-β-D-thiogalactopyranoside (IPTG).

Usage and Biology

The lac repressor,LacI, is a DNA-binding transcription factor that normally represses the transcription of the operon which is involved in the catabolism of lactose. In this repression system, LacI binds to two operators, and formation of the repressor loop is critical (Egan and Schleif, 1993). This repressor binds in tandem to inverted repeat sequences that are 21 nucleotides long and possess conserved motifs. When the physiological inducer allolactose binds to the lac repressor prevents it from binding to the operator and induction occurs. IPTG which is a β-thiogalactosidase nonphysiological and nonphysiological analog, can also induce the transcription (Perros et al., 1996) .

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Citations

[1] Egan, S. and Schleif, R., 1993. A Regulatory Cascade in the Induction of rhaBAD. Journal of Molecular Biology, 234(1), pp.87-98.

[2] Perros, M., Steitz, T., Fried, M., Hudson, J. and Lewis, M., 1996. DNA Looping and Lac Repressor-CAP Interaction. Science, 274(5294), pp.1929-1932.